Drying and pulverizing apparatus with recirculation of material



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igzag relationship with y is perforate and material is pulverized by 21 along the upper tray. The the material back toward the 963 Sears et al....... 966 Helming et al............ Primary Examiner-F rank T. Yost g and pulverizing apparatus includes a ppermost tra III-.1111

[45] Patented Dec. 15, 1970 3089653 3,] 12,078 [73] Assignees By mesne assignments, to James D. 3 289 950 MacGregor, Clarence J. Becker, Arthur C. Becker and Andrew J. Dalman, a f ti l pal-t interest Attorney-Price, Heneveld, Huizenga & Cooper ABSTRACT: A dryin series of vibrated trays arranged in z respect to one another. The u the lower trays are solid. The hammer mill after migration [54] DRYING AND PULVERIZING APPARATUS WITH RECIRCULATION OF MATERIAL hammer mill functions to hurl operation.

DRYING AND PULVERIZING APPARATUS WITH RECIRCULATION OF MATERIAL This application is a continuation-in-part of application Ser. No. 585,956 filed July 18, l966, now US. Pat. No. 3,460,768, date Aug. 12, 1969 the latter application having been made by the same inventor and assigned to the same assignee as this application.

This invention relates to a method of and/or apparatus for treating material and, more particularly, to a method and apparatus for drying and pulverizing material to render it more transportable and/or reusable. This invention relates, more specifically, to a novel method and/or apparatus for reintroducing material which has completed the drying and pulverizing process into the apparatus so as to mix it with material which is not yet been completely dried and/or pulverized in such a manner as to increase markedly the speed and efficiency with which the drying and pulverizing process is executed.

U.S. Pat. application Ser. No. 565,956, now U.S.,Pat. No. 3,460,768, of which this application is a continuation-in-part, discloses and claims on apparatus for and a method of treating offalous material wherein there is provided a series of trays positioned in generally zig-zag relationship within a heated enclosure. The trays are vibrated within the housing in such a manner as to cause material to migrate therealong and, thus, through the heated enclosure. The uppermost of the trays has a perforated bottom. A hammer mill is positioned at the downstream extremity of this upper tray. This hammer mill functions to pulverize the partially dried material and hurl it upwardly toward the upstream end of the upper tray. The

material is recirculated on the upper tray until it is sufficiently I dry and particulate to pass through the perforations therein. After such passage, the material is dried further as it migrates along the series of lower trays. After emerging from the lowermost tray, the material is collected and blown into a suitable storage bin or the like.

The apparatus and method illustrated in the noted copending application has been markedly successful in the drying and pulverizing of materials of the type desired. Some tendency does exist, however, for the uppermost tray to become clogged when the material being treated is extremely wet. This clogging is caused, primarily, by the tendency of the material to resolidify or coagulate into a unitary mass even subsequent to its being broken into small pieces by the hammer mill. Drying can be effected most efficiently, of course, when the material is semiparticulate so that more surface area can be exposed to the circulating heat. It is an object of this invention, consequently, to provide a method of and apparatus for treating material of the type described wherein resolidification or coagulation of the material during the initial drying and pulverizing stages is retarded substantially.

It is an object of this invention, more particularly, to provide a method of an apparatus for treating particulate material wherein the material being treated will be effectively dried and particulated despite the fact that it is extremely wet upon introduction into the apparatus.

It is a further object of this invention to provide a method and apparatus of the type described embodying a novel recirculation structure capable of insuring the availability of material which has already been processed for introduction into the drying and pulverizing cycle.

It is an object of this invention, additionally, to provide such a device and method wherein that portion of the dried material exceeding the requirements of the recirculation system is automatically diverted to a conveying mechanism for movement to a suitable storage location.

These as well as other objects of this invention will be readily understood by those skilled in the art with reference to the following specification and accompanying drawings in which:

FIG. 1 is a side-elevational view, partially in cross section, of the novel apparatus;

FIG. 2 is a fragmentary, perspective view of the lower, forward extremity of the apparatus;

FIG. 3 is a fragmentary, perspective view of the material collection assembly;

FIG. 4 is a fragmentary, perspective view of the elevator. reservoir and mixing assembly;

FIG. 5 is a side-elevational view, partially in cross section, of the elevator, reservoir and impeller assemblies;

FIG. 6 is a fragmentary, front-elevational view, partially in cross section, of the structure shown in Fig. 5; and

FIG. 7 is a cross-sectional view taken alongplane VII-VII of FIG. 6. I

Briefly, this invention comprisesa method of an apparatus for processing material wherein the material is partially dried initially, then subjected to the pulverizing action of a hammer mill or the like, and thereafter dried further. This invention comprises particularly the improvement in the method and apparatus noted above wherein at least a portion of the material which has been initially dried and pulverized is recirculated and mixed with material which has not yet been further dried.

Throughout this specification and the appended claims the term offalous material" is utilized to describe types of material which are accrued as byproducts in the operation of many different types of operations. The term includes, but is not necessarily limited to, such material as the droppings and other waste materials which accumulate in the commercial production of animals, sewage, garbage or other types of refuse, and evisceral matter which is a byproduct of slaughtering concerns. More broadly, the term includes all types of products which are relatively moist and bulky in relation to any fertilizing value, food value or other usable characteristics which they might possess. This is not to imply, however, that the method and apparatus set forth herein is limited solely to the treatment of offalous material. Rather, the system is adaptable for use wherever it is desirable to render any type of moisture containing material more easily usable and/or transportable by drying it.

Referring now to the FIGS., a preferred embodiment of this invention will be described in detail. FIG. 1 illustrates broadly the drying and pulverizing apparatus as comprising a housing 10 having upright supports 11 and horizontal supports 17. The housing is covered about its periphery with suitable sheet material 12 such as sheet metal. Positioned above housing 10 is a stack 13 communicating with the interior thereof. Stack l3, conveniently, may include a cover 14 selectively actuated by a solenoid 15 as a means of minimizing exposure of the ap paratus to the elements. Stack I3 is open by the solenoid 15, thus, only when the drying and pulverizing apparatus is operating. In order to maximize the ease with which the apparatus may be moved from location to location, there can be provided conveniently a pair of skids l6 beneath the frame thereof.

The hopper assembly, indicated generally by the reference numeral 20, comprises an endless belt 21 suitably passed about drive and idler rollers 22. The endless belt 21 is activated selectively by means of a motor 23 operating, preferably, under the command of a load sensor assembly 31. An adjustment assembly 24, conveniently, is provided to compensate for stretching and/or shrinking of endless belt 21.

The details of the housing, hopper assembly and hopper level sensor assembly as well as the tray assemblies to be described hereinafter are disclosed and described fully in the copending application noted previously. Insofar that application is necessary to a thorough understanding of the instant invention, it is incorporated specifically by reference herein.

The upper tray assembly is indicated generally by the reference numeral 30. Upper tray assembly 30, as is disclosed particularly in the noted copending application, comprises an elongated, perforate bottom having upstanding sides. The upper tray assembly 30 is positioned within the housing 10 in the manner indicated generally in FIG. 1 and, conveniently, is provided with a load-sensor assembly 31, the details of which are also described in the noted copending application.

The post-heating tray assembly, indicated generally by the reference numeral 35, comprises an upper tray 36, a middle tray 37 and a lower tray 38. Trays 36, 37 and 38 are disposed in zig-zag relationship in the manner indicated in order to minimize the space occupied by the apparatus. As disclosed in detail in the noted copending application, the material migrates along tray 36, passes onto tray 37, passes onto tray 38 from tray 37 and is thereafter collected in a manner to be described in detail hereinafter.

The hammer mill assembly 40 is positioned at the lower or downstream extremity of upper tray assembly 30. This assembly, as also disclosed in detail in the noted copending application, and includes a central shaft 41 having a series of pivotable hammers 42 carried thereabout by suitable side brackets'and shafts. The hammer mill assembly 40 rotates withinthe curved guard 43 in such a direction as to .hurl the material engaged thereby back toward the upstream extremity of upper tray assembly 30 i.e., clockwise as viewed in FIG. 1.

The upper tray assembly 30 and the post-heating tray assembly 35 including trays 36, 37 and 38 are vibrated during operation of the apparatus by means of the vibrating assembly 45. This assembly includes a pair of shaker plates 46 and a series of straps 47 interconnecting the various trays of the upper tray assembly 30 and the post-heating .tr'ay assembly 35. The plates 46 are jogged eccentrically by an eccentric mechanism 48 run from a suitable drive motor 49. Some of the straps 47, as also noted in detail in the above mentioned copending application, are pivotably mounted while others solidly interconnect the various trays.

The heater assembly, indicated generally by the reference numeral50, includes a combustion chamber 51 having a conventional oil or gas gun 52 positioned so as to fire thereinto. The gun 52, conveniently, may be provided with an exterior housing 53 to shield it from the elements.

As described to this point the drying and pulverizing apparatus illustrated in rather cursory fashion in FIG. 1 is identical to the apparatus shown and described in detail in the noted copending application of which this application is a continuation-in-part. A brief review of that application will indicate clearly to those skilled in the art the structural and functional aspects of the apparatus. Briefly, as a means of aiding in a thorough understanding of the instant invention, the material to be processed is located into the hopper by any conventional conveyor assembly. When the amount of material being stored within hopper 20 reaches a predetermined level, the apparatus is activated by the level-sensor assembly and material conveyed from the hopper onto the upper or upstream" extremity of upper tray assembly by movement of the endless belt 21. The vibration of the upper tray assembly 30 causes this material to migrate downwardly toward the hammer mill assembly 40. During'the time that the material is migrating along upper tray assembly 30, it is partially dried by the gases from combustion assembly 50 which pass either through the perforations in the bottom of the tray or around the 'hammer mill assembly 40 prior to exiting from stack 13.

When the material reaches the downstream extremity of upper tray assembly 30, it comes into contact with the hammer mill 40 and the pulverizing process is initiated. Hammer mill 41 rotates in a clockwise direction as viewed in FIG. 1 and, thus, the material in contact therewith is hurled back toward the upstream extremity .of upper tray assembly 30. This process is repeated continuously, until the material is sufficiently particulate to pass through the perforations in upper tray assembly 30 onto tray 36 of the post-heating tray assembly 35.

The vibration of the post-heating trays 36, 37 and 38 causes the now particulate material to migrate along trays 36, 37 and 38 in zig-zag fashion. During this migration, it is subjected constantly to heat from combustion assembly 50 and, thus, further dried to the desired moisture level. When the material passes off from tray 38, it is dry and particulate and may be utilized or disposed of thereafter in any desired manner.

There exists a tendency, as noted earlier in the specification, for the material to recoagulate on the upper tray assembly 30 subsequent to its being initially pulverized and hurled upwardly thereupon. This recoagulation effects detrimentally to some extent, depending upon the types of materials being processed, the speed at which the drying and pulverizing process may be carried out and, thus, the capacity of the apparatus. The instant invention, a preferred embodiment of which is illustrated in FIGS. 2 through 6, substantially reduces this tendency toward recoagulation on the upper tray assembly and, thus, increases markedly the overall efficiency of the apparatus.

Referring initially to FIGS. 1, 2 and 3, as the completely dried and pulverized material passes from the downstream extremity of post-heating tray 38, it is routed into operative relationship with a collection assembly 60. The collection assembly 60 includes an elongated housing 61 having an auger 62 positioned therein. Auger 62 is rotated by means of shaft 63 which is suitably journaled within frame of the apparatus as indicated at 64: A drive sprocket 65 is provided for rotating shaft 63 and, thus, auger 62. The housing 61 is provided, of course, with suitable apertures or other means for permitting the dried material to come into conveying relationship with the auger 62. The auger 62, thus, moves all of the material issuing from post-heating tray 38 and, thus, all of the material which has been dried by the apparatus to the right as viewed in FIGS. 2 and 3 into conveying relationship with the elevator assembly 70.

Elevator assembly 70 (see particularly FIGS. 5, 6 and 7) comprises an elongated, upright housing 71 having a rear wall 79. Rear wall 79 has an aperture 72 therein (see FIG. 3) through which the material is conveyed into housing 71 by the collection assembly 60. The lower extremity of housing 71 has suitably secured thereto a boot 73 into which the dried material passes after exiting from housing 61 under the influence of auger 62.

Positioned within housing 71 is an endless chain 74 borne at each of its extremities by suitable sprockets 75. Attached to the exterior periphery of the chain at suitable intervals are a series of lift pads. 76. The interior periphery of the chain, of course, is bounded by suitable shields 77 which prevent the material being elevated from passing through the apertures in the chain and back down to the boot 73 prior to reaching its final destination. Shield 77 has positioned thereacross a shelf 78 at the position shown in FIG. 5, the purpose of which will be discussed hereinafter.

Positioned at the upper extremity of elevator assembly 70 and, conveniently, formed integrally therewith is the reservoir assembly 80. The reservoir assembly has an overhanging section 81 (see FIGS. 4, 5, 6 and 7) with a converging bottom 82. Bounding the reservoir assembly in conjunction with the rear wall 79 of the elevator housing 71 is a vertical sidewall 83 (see FIG. 7). As the material is elevated upwardly by the pads 76 on elevator assembly 80, it is dumped over the wall 83 into the reservoir assembly 80 and, thus, isolated from the channel within which the elevator assembly runs.

The mixing assembly, indicated generally by the reference numeral 90 and shown best in FIG. 4, comprises an elongated tube 91 having an elongated aperture 92 therein. Rotatably mounted within the tube 91 is an auger 93 which, when rotated, conveys material from the hopper portion 82 of the reservoir assembly 80 through the tube 91. This material issues from the elongated slot 92 in tube 91 and falls onto the upper tray assembly (see FIG. 1) adjacent hammer mill assembly 40. The auger drive mechanism, preferably, incorporates an electric clutch 94 or the like driven from a suitable sprocket 95. Clutch 94 may be utilized to activate selectively the auger 93 and, thus, the reintroduction of processed material into the apparatus in accordance with any predetermined control scheme without the necessity of providing a separate drive motor for auger 93.

Referring now specifically to FIGS. 4 through 7, it will be noted that the rear wall 79 of elevator housing 71 has an aperture '85 therein. Aperture communicates between the reservoir assembly 80 and the interior channel 86 of the elevator assembly 70. Channel 86 is bounded by the rear wall 79 of the elevator housing 71, the two interior shields 77 and. the cover plate for the elevator housing. From the examination of FIGS. 5 and 6, it will be noted that the aperture. 85 is positioned substantially above the hopper 82 of reservoir assembly 80 and when the machine is activated initially, the material which is not recirculated via mixing assembly 90 will build up in the reservoir section until it reaches the height of aperture 85. Upon obtaining this height, the material will fall through the aperture 85 and into the channel 86. The material will then drop downwardly within channel 86 until it strikes step 78 which forms effectively a bottom for the channel.

The impeller assembly 100 (see FIGS. 4, 5 and 6) comprises a centrifugal housing 101 having a suitable centrifugal fan (not shown) therein which, conveniently, may be driven directly from the hammer mill shaft 41. The centrifugal fan housing 101 has an intake 102 and an output 103 as will be readily appreciated to those skilled in the art. An aperture is provided in the rear wall 79 of the elevator assembly opening into the channel 86 closely above step 78. This aperture communicates with the intake 102 of the compressor assembly 100 by means of a sleeve 104. Another aperture, 105 (see FIG. 6) is provided in the cover for the elevator assembly. Aperture 105 is positioned generally concentrically with the sleeve 104 and, thus, the intake to compressor 100.

Air is drawn into the intake of the compressor 10] through sleeve 104 and aperture 105. The stream of air picks up and suspends the particular material which has been deposited on step 78 from the reservoir and this material is exhausted at outlet 103. By placing a flexible hose or the like in communicating relationship with outlet 103, the material may be pumped under the influence of the compressed air to any desired storage or use location.

The particular sequence of operation of the mixing auger 33 will depend a great extent, of course, on the characteristics of the material being dried and pulverized. It may be desirable, for example, to initiate the mixing of the processed material with the partially processed material on each occasion during which the endless belt 21 is rotating and, thus, introducing unprocessed material onto upper tray assembly 30. If such is the case, the electric clutch 94 may be connected to the control for hopper motor 23. In such a situation, the mixing auger 93 will rotate and drop the processed material onto the tray whenever the endless belt 21 is in operation. Similarly, the amount of material issuing from the aperture 92 whenever the auger 93 is in operation will depend upon the characteristics of the material being processed. This can be controlled in a number of ways; for example, by changing the size of aperture 92, the diameter of sprocket 94 or the like.

Once the system parameters for maximum operating efficiency with a particular material have been derived, the control system for the machine may be suitably programmed. As the wet material introduced onto upper tray assembly 30 by the endless 21 reaches the hammer mill in its partially dried state, the completely processed material issuing from aperture 92 will mix with it. The mixing of the processed material, of course retards significantly the tendency for the nonparticulated material to coagulate upon being thrown back onto the upper tray assembly 30 and, thus, markedly improves the capacity of the apparatus.

The provision of the reservoir assembly 80 insures the availability of processed material for mixing with the unprocessed material by mixing assembly 90. After the apparatus has been in operation for a short period of time, processed material will begin issuing from the downstream extremity of tray 38. This material will be accepted by the colleetion assembly 60 and moved by the auger 62 into the boot 73 of elevator assembly 70. Once in the boot of the elevator assembly, the material will be picked up by the lift pads 76 on endless chain 74 and elevated to the upper extremity of the elevator assembly. At this point, the material is dumped over the wall 83 into the reservoir assembly. 7

That portion of the processed material necessary for the recirculation or mixing assembly 90 will be removed from the reservoir by the auger 93. The remainder of the processed material will build up within the reservoir until it reaches the height of aperture 85 at which time it will fall through channel 86 toward step 78. Upon reaching the level of step 78, the material will be drawn through the sleeve 104 and into the compressor assembly 100. The material will be suspended within the stream of compressed air and issue from outlet 103 to the desired storage location.

While a preferred embodiment ofthis invention has been described in detail, it will be readily apparent to those skilled in the art that many other embodiments may be conceived and fabricated without departing from the spirit of the instant invention. Such other embodiments are to be deemed as included within the scope of the followingclaims unless these claims, by their language, expressly state otherwise.

We claim:

1. In an apparatus for drying and pulverizing material having a housing; a plurality of trays positioned within the housing at angles to the horizontal, each of the trays having a discharge opening positioned such that material passing therethrough falls into the next lower receiving tray; means for supplying material to be treated to the uppermost of said trays; means for activating the trays whereby the material migrates from the uppermost to the lowermost thereof; means for heating the material during said migration; and means for pulverizing the material positioned along the path of migration thereof; the improvement comprising means for collecting at least a portion of said material at a point in said apparatus downstream from said pulverizing means and means for mixing the material so collected with material on one of said trays which is upstream from said pulverizing means.

2. Theapparatus as set forth in claim 1 wherein the uppermost of said trays is perforate and wherein said pulverizing means comprises hammer mill means positioned at the downstream end of said perforate tray, said hammer mill means being adapted to hurl material engaged thereby back upwardly on said perforate tray until it is sufficiently particulate to pass through the perforations in said perforate tray.

3. The apparatus as set forth in claim 2 wherein said pulverized material is mixed with the other material adjacent said hammer mill means.

4. The apparatus as set forth in claim 1 wherein said collecting means collects the material as it issues from the lowermost of said trays.

5. The apparatus as set forth in claim '4 wherein said collecting means collects all of the material issuing from the lowermost of said trays and which further comprises means for transporting that portion of the material issued from said lowermost tray which is not required by said mixing means to a suitable storage facility.

6. The apparatus as set forth in claim 1 which further comprises means communicating with said mixing means for storing a quantity of the collected material for use by said mixing means.

7. In an apparatus for drying and pulverizing material having a heated enclosure means for conveying the material through said enclosure to dry it, and pulverizing means located intermittent the extremities of said conveying means for pulverizing the material as it passes thereby whereby said material is first partially dried, then pulverized and then further dried, the improvement comprising: said pulverizing means being a hammer mill rotating in a direction to cause the material to be thrown upstream of said conveying means; and means for collecting at least a portion of said material which has been further dried and mixing it with the material which has not yet been further dried.

8. In an apparatus for drying and pulverizing material having a housing; a perforate tray positioned within the housing at an angle with respect to the horizontal; access means wherethrough material may be placed on said tray at the upper section thereof; means for actuating said tray such that said material tends to migrate from said upper section to said lower section thereof; pulverizing means positioned in operative relationship with respect to said lower section to receive said material and pulverize it, said pulverizing means being operative to hurl said material back toward the upper section of said tray subsequent to contact therewith whereby said material is recirculated on said tray until such time as it is sufficiently particulate to pass through the perforations therein; means for heating said material as it circulates along said tray; and means positioned below said tray for catching said material as it passes through said perforations, the improvement comprising means for collecting at least a portion of said material after it has passed through said perforations and mixing it with material on said perforate tray 9. The apparatus as set forth in claim 8 wherein said catching means comprises:

a plurality of receiving means positioned below said perforate tray in zig-zag fashion, each of said receiving trays having a discharge opening at its lower end, said discharge opening being positioned such that material passing therethrough falls onto the upper section of the next lower receiving tray;

means for vibrating said receiving trays such that said material tends to migrate from the upper sections to the lower sections thereof; and

means for heating said material as it migrates along said receiving trays.

10. The apparatus as set forth in claim 9 wherein said collecting means is positioned at the discharge opening of the lowermost of said receiving trays.

11. In an apparatus for drying and pulverizing material having a housing; a plurality of trays positioned with the housing at angles to the horizontal, each of the trays having a discharge positioned such that material passing therethrough falls onto the next lower receiving tray; means for supplying material to be treated to the uppermost of said trays; means for activating the trays whereby the material migrates from the uppermost to the lowermost thereof; means for heating the material during said migration; and means for pulverizing the material; the improvement comprising means for collecting at lease a portion of said material at a point in said apparatus downstream from said pulverizing means and means for mixing the material so collected with material which is upstream from said pulverizing means.

12. The apparatus as set forth in claim 11 wherein the uppermost of said trays is perforate and wherein said pulverizing means comprising hammer mill means positioned at the downstream end of said perforate tray, said hammer mill means being adapted to hurl material engaged hereby back upwardly on said perforate tray until it is sufficiently particulate to pass through the perforations in said perforate tray.

13. In an apparatus for drying and pulverizing material having a heated enclosure, means for conveying the material through said enclosure to dry it, and pulverizing means for pulverizing said material at least before complete drying, the improvement comprising; said pulverizing means being a hammer mill rotating in a direction to cause the material to be thrown upstream of said conveying means; and means for mixing at least a portion of said material which has been dried with material that has not been pulverized. 

